On top of what's already been said, to your question specifically of what the devs are doing - a lot of the time it's nothing out of the ordinary as the Ops teams are the ones conducting the maintenance. There will likely be a dev or devs on call, but that's routine anyway so it's ultimately just another day for them. Sure, when big patches are pushed they're typically more attentive to the process - but even then, they're essentially informed observers.